


Sanster Week 2017

by yastaghr



Series: Sanster Continuum [2]
Category: Undertale (Video Game)
Genre: Adoption, Bad Pick-Up Lines, Broken Bones, Chara Has Their Own Body, Chara Possessing Frisk, Crying W. D. Gaster, Cuddling & Snuggling, Depression, F/F, Flowey Reset time period, Flowey is not a character but he still causes trouble, Fluff and Angst, Gaster Needs a Hug, Good Chara, Good W. D. Gaster, Goopy W. D. Gaster, Grief/Mourning, Illnesses, Injury, M/M, Magic, Magic and Science, Medical Conditions, Medical Device, Mpreg, Nerdiness, No More Resets (Undertale), No Smut, Nonbinary Chara and Frisk, Pacifist Frisk, Poor Sans, Post-Undertale Pacifist Route, Post-Undertale Pacifist Route - "I want to stay with you.", Pranks and Practical Jokes, Pre-Accident W. D. Gaster, Pre-Undertale, SAVED Asriel Dreemurr, Sad, Sans Needs A Hug, Sanster, Science, Science Experiments, Science Fiction, Scientist W. D. Gaster, Suspended Animation, The Void, Undertale Saves and Resets, Video Game Mechanics, and by trouble i mean sads, how is that not a tag?, kidnapping by void, mild body horror, mild though, questionable decisions
Language: English
Status: Completed
Published: 2017-08-14
Updated: 2018-02-07
Packaged: 2018-12-15 09:43:48
Rating: Teen And Up Audiences
Warnings: Graphic Depictions Of Violence
Chapters: 7
Words: 9,994
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/11803470
Author URL: https://archiveofourown.org/users/yastaghr/pseuds/yastaghr
Summary: For rag--tag on tumblr's Sanster Week 2017.  The chapters form a loosely connected narrative set after Breeding Machine. If you don't want to read that, just know that Sans is carrying Gaster's child.





	1. Day 1: Pre-VOID Incident

“Sans.”

 

“What’s up doc?”

 

The exasperated skeleton craned his neck to give his shorter colleague the full benefit of his glare. The cheeky prankster’s smile didn’t move an inch. At the table nearby, several scientists, whom he assumed were on break due to the bag of apples slowly disappearing between them, shuffled their seats a little further away.

 

“Why is all of the South corridor upside down? How did you even do that? Now no one from Snowdin, Hotland, and Waterfall can get here!”

 

Sans shrugged his infuriating shrug. Gaster grated his teeth. The scientists exchanged a look, picked up the remaining apples, and made a hasty tactical retreat.

 

Once they were out of hearing distance, Gaster’s scowl evaporated. In its place was a grin. Sans’ smile grew twice as wide, and Gaster had to fight to keep the cycle from continuing. It could only bring bad things.

 

“Stars, Sans, you are a genius! I’ve been trying to think of a way to avoid this “Ice Cruelty Protest” nonsense all day. And you just flipped the entrance so they can’t walk in! Thank you, thank you, thank you!”

 

Sans chuckled, “no prob, g.”

 

Gaster scooped him up and cuddled him close to his chest. Their ribs slotted together ever so slightly, the hidden, protective stomach currently holding their baby pushing against Gaster’s shirt. He hummed, and Sans shivered at the sensation, his skull turning blue. A very satisfying result.

 

“I am sure you wouldn’t object to some kind of reward?”

 

Sans nodded mutely. Both the SOULs inside his chest thumped with excitement.

 

Gaster’s smile turned wicked, “How about a free project? It’s been awhile since we’ve done one of yours. You must be feeling left out.”

 

Sans tried to glare at him, but a dawning realization quickly overtook any less positive emotion.

 

“can we do the transdimensional doorway? please? i know you don’t want to meddle in case interference damages not just our universe, but the other. but i really, really want to see. i mean, pap must be so cool! what if there are stars? we could see stars! or the ocean - what if there’s a universe where we’re merpeople! you’d look so cool with a purple fin. maybe some black scales. or silver!”

 

Gaster gave in. He really didn’t like the idea of interacting with another universe, especially with a child on the way. But Sans looked so happy like this. So adorable. And if there was a world where monsters lived on the surface, he’d want his boyfriend to see it. 

 

“Alright. I’ll get the blueprints. You can go around and see if anyone else wants in on this nonsense.”

 

The sound that Sans made as he rolled out of Gaster’s arms and ran out the door was probably best approximated by the word squee. He really was so cute sometimes. Working on this project would be more than worth it.

 

* * *

 

Sans pouted from his chair in the observation room as Gaster made some last minute preparations on the experiment room floor. He’d given birth a week ago, damn it. He didn’t deserve to be treated like this! Yeah, the birth had gone pretty badly. Yeah, the kid was currently in a suspension tube until their bones were stabilized enough to handle air. Yeah, his magic hadn’t returned yet. Yeah, his bones still had cracks that his brother was worried weren’t healing. But that didn’t mean he couldn’t handle this!

 

Gaster didn’t agree. He’d all but tied Sans down with chains to keep him from trying to help with this. It was Sans’ idea in the first place! He should be down there! But Gaster was the boss, and if he said Sans was banned from active experimentation, there wasn’t much the short skeleton could do. Pouting was among those things.

 

So he was forced to watch as Gaster input the coordinates HE’D FOUND that corresponded to this place, this time, this universe. He was forced to watch as Gaster set the target. It only a few numbers away, supposedly the coordinates of this world three minutes in the future. They were starting out small - things worked better that way. They didn’t know if this machine could even work. They needed to test one thing at a time - that was how good scientists did things: slowly, tediously, and repetitively. If this test succeeded, they’d be performing it again and again for the next two weeks, moving up from 3 minutes to 30 minutes a little bit at a time.

 

With the coordinates in place, Gaster reached into his breast pocket and pulled out a miniature tape recorder. They were now lab-standard - per Sans’ request. It made typing up reports easier for everyone, and saved paper! Win-win!

 

The doc started speaking. Sans couldn’t hear him. Alphys hadn’t installed the intercom system yet. Thus, Sans had to watch and guess what his lover was saying. It was actually kinda cute, the way Gaster paced around the room, checking every dial, removing a few stray hairs, and occasionally stopping in mid-speech to smack himself in the face. Classic g. 

 

After hours of preparation (okay, fifteen minutes, but who’s counting?) Gaster finally went over to the door. Simple enough concept, right? Open it, and you can pass from one place to another. Close it, and they’re back to being separate. All they were doing was just...playing with the wall. 

 

He stared at the thing for a minute. A minute! Sans understood dramatic tension as well as any monster, but this? Was excessive. It wasn’t a pause - it was torture!

 

When Gaster finally reached out and opened the door, everything went to shit. 

 

For a split second, the doorway revealed the lab. It was rotated 180deg, but Sans would recognize it anywhere. The device had worked!

 

Then the world stuttered. It was like an earthquake, from what Sans understood of them. Everything started shaking, stuff was falling off the walls, and he was so unsteady he was seeing double. No. Wait. There really were two of everything - like someone had copied the universe and pasted it just a little bit to the left.

 

Then it settled, and there was one of everything again. There was one major difference, however. The doorway was filled with black. The kind of black that doesn’t reflect light, it absorbs it. And then the black was spreading, thick tendrils winding their way out into the room. Gaster took a step back. Two. Then he turned and ran for the blast doors.

 

Everything within five feet of the doorway was swallowed up in seconds. Then the tendrils found the control module for the experiment room doors. They dragged it into the door as if it was a pillow. A two-ton piece of machinery bolted to a slab of steel two feet thick, reduced to nothing. The blackness swallowed it whole.

 

Sans was on his feet now, screaming and banging on the glass with all his might. He could feel the bones in his arms protesting. He didn’t care. The tendrils had grabbed the table now and were banging it against the door frame, trying to bring it through. There wasn’t much else left in the room. There were two chairs that lived behind the table, and there was Gaster. He was pressed against the exit. He was shaking so violently he looked like a blender. His magic was sparking, bullets forming around him. They fired, but the black ooze swallowed them up like it had the module. Attacks were useless.

 

Gaster looked up at the observation room window. Sans was still banging, screaming at Gaster to blast the doors, pry them open with a bone, to do something! He knew it would never yeild, but…

 

Gaster smiled sadly up at him. He blew a kiss. Sans was full out sobbing now, his tears leaving blue residue on the glass. The tendrils were only inches away, the chairs long gone into the void.

 

Gaster held up one hand with the thumb, pointer finger, and pinky finger extended. Then he bent the thumb and pinky in. Purple tears stained his shaking fingers as he rotated the pointer in circles. Over. And over. And over. Then the tendrils had him, and he was gone.


	2. Day 2: In the Void/Mourning

In the moment the Barrier shattered, everyone was happy. Their greatest dream was finally coming true, right? They could finally see the stars and the sun. He should be happy, right? So why was it that he felt worse than he had before?

Sans didn’t follow his brother when Papyrus ran down the mountain. He knew that Undyne would look out for him. A short, weak little skeleton wasn’t going to do much good. He knew they would probably be sleeping in the mountain for a while, too. From what he’d heard, humans had an obsession with paperwork. They’d probably take ages to get things straight. And if they were going to be sleeping in the mountain anyway, why shouldn’t he get a headstart? No one would notice. It was fine.

So as Frisk and their friends raced to meet the new world, Sans descended into the old. He minced his way through the flower-filled throne room. He slouched through the grey walk above New Home. The color did little to increase his spirits. Seriously, why did they paint the place like that? Living in the Underground was gloomy as it is.

He made it to the elevator to the CORE and pressed a button. It was a worn button, the kind you might look past. Heck, most people didn’t even see it there. But he knew that button. He’d pushed it hundreds, no, thousands of times. And yet, it would also be true to say that he had never pressed it before. Timelines were tricky like that.

The elevator hummed to life. It was a little clunky after the weeds vines had messed with the gearing, but it still ran and ran steady. Anyway, if he died here no one would know. Well, the kid would know. No one would be able to use this elevator to reach the surface. They’d probably RESET or LOAD or whatever the word was. He’d barely even know this had happened. He wondered if he’d done this before. Probably.

Finally the elevator settled at the desired floor. The silver doors slid open to reveal a dusty expanse of black. Not a living, all consuming black that sucked you in and spit you out. He knew that dark, and this wasn’t it. It wasn’t a creepy, horror-movie-esque darkness, either. It was just the black of a large, cavernous room that had no windows and didn’t have the overhead lights turned on yet. Sans flipped the switch.

Yep. Still as dorky as ever. The replicas of human sci-fi icons, most of which didn’t work, still lined the walls of the main entry. The staff had been so proud of them. He still couldn’t help but run loving phalanges over the tall blue box. It was his baby, and without it, he wouldn’t know as much about timelines and shortcutting as he did now.

He tore his attention away from the box. It was his, but it wasn’t what drew him here. His hands wandered over to the tube beside it. Inside, suspended in a faintly blue and purple liquid, was a miniature skeleton. There were no sockets in its skull. The area was smooth and unmarked. And grey. The whole skeleton, in fact, was grey.

“hey, kid. been awhile since i’ve seen you, huh? haven’t been able to come down here. don’t take it personal. it ain’t because of you.”

Sans slid into a tailor’s seat in the half-inch thick layer of dust. It wasn’t monster dust - at least, he didn’t think it was. Not all of it, certainly. But if no one could see the button that brought them here, how long had this room been sitting untouched? How could it even exist in the first place? He didn’t know. He didn’t really care.

“you haven’t seen your papa, have you?”

Where had that come from? He hadn’t even been thinking about...oh. Was that why his SOUL was hurting? Gaster had always wanted to see the surface. More than anything. Getting up there without him was...wrong.

“daddy’s been looking all over for him. i’m...really worried. his bones always get creaky if he doesn’t take his medicine. it’s been...i have no idea how long it’s been. or if it has been at all. but he probably needs to take the next dose.”

A small poof of dust drew his attention. He looked down to see blue tears making a mud puddle beneath him.

“daddy really, really misses him. can you give him a message? you know, if he stops by.”

Sans wiped away the tears as best he could. No point in letting the others see him like this.

“tell him i’ve got my phone turned all the way up, and i’d love to schedule a date under the stars. got a nice telescope and everything. some nerd gave it to me. didn’t know why he bothered at the time, but now,” He sniffed, wet and ugly, “i’d really like to test it out on the top of this mountain.”

He stood up, leaning on the tube that contained the child his little brother never got to meet. He couldn’t. Without both their fathers’ magic, they’d never be able to grow strong enough to leave the tube. In this timeline, they never could have even existed.

“heck, if you see him, we might be able to get you out of that suspension liquid. so please,” Sans closed his eyes and breathed heavily, “please, i just want to find him. i can’t- i don’t- i miss him.”

He dragged his slippers through the dust all the way over to the door. He hesitated with one hand hovering over the light switch.

“daddy loves you, babybones. see ya around.”

The lights went out. The elevator doors opened. Closed. Rumbled. Faded.

In the pitch black, clinging, possessive black that remained, a shadowy figure beside the tube bent towards it. Then it dipped, folding almost in half. It saw the muddy puddle of tears. It added to it. In light, any light at all, the tears would almost appear to be purple under the black.


	3. Day 3: Reunion

Sans was trying so hard not to get his hopes up. Yeah, the kid had promised they wouldn’t RESET anymore. But how could he know that had been the problem? What if he’d forgotten to carry a one somewhere? What if he’d used the wrong value for the universe’s growth rate? What if breaking the Barrier had changed something?

 

But on the other hand, he couldn’t help but hope. The fluctuations in temporal linearity had ceased. The flower was no longer a flower thanks to Alphys’ ingenuity. Apparently he was the long-dead son of the king and queen? That had been a fun conversation. They were trying to make it work, but having three kids living in their house, cheering them on, and generally keeping them too busy to argue helped. 

 

That’s right. Three. Alphys made a robot, and Frisk pulled their SOUL in half and SURVIVED. That was impossible, but what wasn’t with this kid. Then they’d shoved the SOUL-half that hadn’t vanished back into their chest into the robot. It came to life. And thus, the king and queen got both their kids back. Who would have thought?

 

So the kid had no reason to RESET, and no one else could. He had every reason to believe this would work. But if it didn’t? He’d be devastated. Not for the first time, either. So he was trying his hardest not to hope.

 

Still, he had to try it sometime, right? And today was as good a day as any. Papyrus was away at some extreme adventure-y thing that Undyne had signed them both up for. Tori and her gang were out on a fieldtrip. Asgore had been convinced (read: forced at glare-point) to be one of the male chaperones for the trip. Alphys was enjoying a day at the spa with Bratty and Catty. The three hadn’t gotten together in ages. 

 

All that meant that if he accidentally sucked the apartment building into a black hole like Gaster’s lab had been, well, no one would notice until the end of the day. Also, he’d be the only one dragged in. No casualties anyone couldn’t live without.

 

So standing in front of the Transdimensional Doorway wringing his hands was a complete waste of energy and time. He just needed to reach out and…

 

Nothing. That was all that lay on the other side of the grey wood. Nothing. At least it wasn’t a clinging void reaching out and swallowing him whole. But it wasn’t Gaster leaping into his arms and knocking both of them to the floor, either. Pretty neutral then.

 

Working up what little courage he possessed, Sans stuck his head into the dark. His phalanges gripped the sides of the doorframe like his life depended on it. It kinda did, but that was beside the point. The point was that every single bone in his body was tense.

 

On the other side of the doorway, greyish, vaguely black, mildly white soup was everything. There was no floor. There was no ceiling. There was only fog and silence.

 

Sans broke the silence with a cough. What did you say in a situation like this? ‘Gaster, can you hear me?’ No, that sounded too...fake. ‘Doctor Gaster, your ten o’clock appointment is here.’ Definitely not. ‘Hey, love, I’ve been looking all over. I’d kinda like to take you back.’ That sounded creepy and desperate. He wasn’t creepy, right? He’d been raising his hand to the ‘desperate’ for ages. 

 

“yo, doc. i think i’ve figured out what my problem is. i’ve been missing you all these years.”

 

Yeah. Nailed it. Totally not weird at all.

 

It must have been funnier than he thought, because distorted, guttural laughter filled the space that was not space. It sounded broken, both in the way that bubbles rising out of water sounded, and in the sad, pathetic kind of way. But somewhere underneath the distortion and the pain and the effects of the space itself, that sound was familiar.

 

“g?”

 

Sans turned his skull this way and that, searching for any sign of his long-lost lover. He saw nothing. It hurt. Had he fixed this device just to torture himself with the echo of that wonderful laughter?

 

“gaster, if that’s you, please,” Sans voice broke, but he pressed on, “please give me something to work with here. i-”

 

“S_sAaaAaa-aN5s?”

 

Unbelieving. That was what the voice sounded like. As if it had been taunted hundreds of times only to be betrayed, and yet still a glimmer of hope remained. That tone in his lover’s voice...it made Sans’ SOUL ache. It felt too much like his own.

 

“yeah, g. it’s me. can you see me?”

 

“H_h*haAallllllllllfF.”

 

Half? What did that mea- oh!

 

“the top half?”

 

“YyEE_Es!!!”

 

Excitement was starting to creep into Gaster’s voice. Guess hallucinations didn’t show up as only a top half.

 

“can you come over here? i, uh, can’t see you right now.”

 

“Oh_h_H.”

 

Slithering sounds ensued. Well, not exactly slithering. More like what you might get if a snake was able to cross a block of oobleck in an echo chamber. But slithering was, like, the base of it. It was easier to say, too.

 

After about a minute of concentrated slithering, a figure emerged from behind Sans. That made sense. He couldn’t crane his neck  _ that _ far around. He wondered what he’d looked like from behind. Did he just end in the middle of a vertebra? Did he have, like, a glitchy white flat segment where his shirt ended? He’d have to ask later. Right now, he was too busy taking the figure in to ask.

 

They were a blob. Like, a straight up B-rated human horror movie blob, not a Moldsmaal or Moldbygg. The color scheme was black; at least it fit with the room. The blob shivered, and a white blob- no, a skull! It was a skull, a familiar skull, rising from the goop! Cracks ran up from one eye socket and down from the other to meet an adorable, growing smile. 

 

Sans went to shout his lover’s name, but found his throat was too thick to manage it. He squeaked like chalk on a chalkboard instead. Gaster’s smile was so wide it threatened to split his skull in two. The purple tears running down his face matched Sans’ own. He was blubbering. Happily! Blubbering happily.

 

When he managed to pull himself together enough, Sans croaked, “gaster, i- i- you can leave. i fixed it! we’re on the surface now, the stars are great, and- and- get over here before i break down again!”

 

Gaster, his skull now stained purple from the corners of his sockets to his chin, nodded and started slithering towards Sans as fast as he could. Actually, looking at him move, it was more of a glomp kinda motion, like a glacier at ultra-super-duper-incredible high speed, or magnetic slime consuming a magnet. Kinda weird to watch. Fascinating, in a science-y way.

 

When Gaster finally arrived after what felt like an eternity, Sans freed his left hand from where it had probably dug a groove into the wood of the doorframe, snatched his lover by the closest bit of black goopiness, and, in a herculean effort of strength (for him at least), dragged Gaster through the portal and into reality.

 

He hadn’t really thought that through. There was a lot of energy involved in an airborne Gaster, and a shaky Sans had no choice but to join in a goopy, headlong tumble across the room. They ended up collapsed against the washing units that lived in the corner. This was an apartment complex, after all; the basement is where the laundry usually lives. At least it hadn’t been Undyne’s Pile o’Armour. That might have been dangerous.

 

The position they’d ended up in lent itself to cuddling, which was fortunate, since that was all the two had in mind. Sans was running his magic and his hands over every inch of Gaster he could reach. Gaster was doing the same. His summoned hands were a little shaky, but that didn’t matter now. Now they were just so relieved and ecstatic to be together again.

 

After what felt like forever but was probably an hour, max, Sans forced himself to say, “you know, eventually we’re going to have to get up, right?”

 

Gaster’s only response was to cuddle him tighter. Sans smiled and nuzzled into him, careless of the tears streaming down his skull.

 

“that’s what i thought.”


	4. Day 4: Hurt/Comfort

It was a few days after Gaster’s return that Sans felt he was recovered enough to go for a walk. It had taken time to remember how to talk as he used to, how to live in an environment in which gravity was a thing he had to worry about, and how to move his new body at any kind of speed. But Gaster was persistent, and soon was walking up and down the staircase of the apartment complex so frequently Sans was worried he’d wear a groove. That was when he decided that a little walk would probably do his boyfriend good.

It was going slow - not because Gaster couldn’t go faster, but because he didn’t want to. He wanted to examine the grass. He wanted to take notes on the birds. He wanted to collect leaves from the pile underneath the brightly colored trees. He wanted to watch the clouds shift in the wind. He wanted to experience everything the Surface had to offer.

It wasn’t until they turned the corner that Sans remembered that other thing the Surface had a lot of. Humans. More specifically, it had humans who...weren’t as nice about monsters being on the surface as Frisk was. More specifically, it had Helen. Helen, with her gel-soaked yellow hair, her too-tight, too-high shoes, and her shrill voice that grated on eardrums Sans didn’t even have. Her shrill voice currently screeching about Demons and Hell as she glared at Gaster, not even noticing Sans.

It wasn’t like it was the first time Sans had heard her do this. Actually, it was the 374th time she’d done it in his presence. You’d think that was enough, but no. Every new monster, sometimes even the same ones over and over, startled this reaction out of her.

What didn’t usually happen (in fact, ever happen) was violence. Gaster, just as startled as Helen, forgot to use his normal voice. He was only trying to reassure her that he wasn’t a threat to anyone. Unfortunately, he did so in a voice that sounded like an eldritch terror from the depths of the VOID (which he kinda was). That...did not go over well.

Helen was now convinced through the stunted, twisted thought process she called logic that she was facing an actual Demon. She reacted in a way she deemed appropriate. It was not, by any means. Throwing a metal water bottle full of gin would hurt even a human, let alone a monster still recovering from the VOID. It would also have hurt Sans, who was standing right beside said monster, mouth gaping. Actually, it would have dusted him, but hey, what’s a little murder between fellow committee members?

The bottle had smashed into Gaster’s semi-blind eye before Sans could stop it. It lodged there. Small cracks spread out from it. Gaster’s skull, bottle and all, tried to retreat into the safety of his blob. The bottle didn’t cooperate.

Sans tore his eye sockets from his injured lover and fixed them on Helen. It was just dawning on her that she might have made a mistake. Sans’ fire-y eye was probably contributing.

“h e l e n.”

She was staring at him with a look of horror. Not the fear and hate she had turned on Gaster. No, this was genuine horror, the terror at an immediate threat that you cannot scare away or beat. Good.

“Y-yes?”

She was starting to draw herself up into her castle of bigotry and entitlement. He couldn’t have that.

“this is gaster. he’s my lover. i just pulled him out of the void five days ago. he’s still recovering. this is his first time out of the building, and he was enjoying collecting leaves and listening to the birds. when you yelled at him, he tried to tell you he meant no harm, and you threw a heavy metal object at his head. how do you think that makes me feel?”

She gulped, “A-angry?”

Sans sighed. All this time, and she still didn’t get it.

“i’m worried and scared that he’s been hurt. i’m disappointed in you. only a little, though. i’ve kinda come to expect it. and i’m sad that this happened, and i’m upset with myself for letting it happen. no-”

Gaster’s head had popped out of his body, sparks of indignation shouting out of his uninjured socket.

“i don’t really believe that, but i feel it. how long is it gonna take, helen, before you get it? monsters don’t react like that. i ain’t gonna blast you, even if i want to. mostly, i just want you out of my sight.”

She sniffed. Ah, there it was. The rationalization, the dismissal, the disgust - in other words, classic Helen.

“It’s no wonder you people were locked under that mountain if you act like this. Letting something like that out where real people are walking? What did you expect to happen?”

Sans’ fists clenched. He hated it when she said things like “you people” and “real people”. But more than that, he hated how she’d just referred to his lover. It was time for revenge.

“i don’t know, helen. what did you expect to happen when you walked out of the house with your makeup like that? last i’d heard, clowns are known to terrify children and adults alike. why are you begging to get punched in the face?”

She made that incoherent screech that Sans had come to know and love. It meant his petty remark had just hit home. She stomped off towards her house, no doubt to spend hours making her makeup look just so. That was usually what she did. He wondered if she’d ever realize he had no idea what he was talking about when it came to that subject. That was what his brother was for. He doubted it.

The blue-cardiganed terror finally dispelled, Sans practically teleported to Gaster’s side. He CHECKed him, terrified his fit of rage had damaged his lover beyond repair. 25/60 HP. Not good, but not as bad as he’d feared. Time to see Toriel.

Sans wrapped his arms around as much of Gaster’s goop as he could reach. He whispered where they were going into the side of Gaster’s skull. Gaster nodded, a summoned hand patting his cheek. Sans smiled bittersweetly back at him, then opened a shortcut beneath them.

 -----

On the other side of the shortcut a mildly surprised Boss Monster set down her glass of tea. Asgore was sitting across the table from her. The two of them had the air of people who had been engaged in a terse discussion before the arrival of two unexpected guests through the ceiling.

It only took a moment for their eyes to take in Gaster’s injury. Then Toriel was up and over. Green magic twined around her fingers. Gaster sighed when it sank in. After a few seconds, she reached up and pulled the bottle out with a sound like a plunger. Magic was weird.

Asgore, on the other hand, had slipped into the kitchen and poured the remnants of the teapot into the large thermos he’d bought for Family Dinner Night. He handed that to Sans over a empathetic look. Sans smiled sheepishly back.

The fizzle of magic drew both their attentions back to Gaster. His skull looked just as it always did, if a bit shiney around the bad socket. Toriel was smiling widely, which Sans took to mean things weren’t as bad as he’d thought they’d been. Her words confirmed this.

“He’s fine. He shall be a little shaken by the recent events, I am sure, but it nothing that a little comfort and cuddling cannot fix. I take it you are amenable to providing this?”

Sans smiled back at her, his grin wide and tinged slightly blue at the edges.

“yeah, tori. it’ll be a sacrifice, but i think i can manage it.”

Asgore snorted. Toriel shot him a look. Sans decided it was time to leave, and, with a little wave neither Dreemur noticed, pulled Gaster through yet another shortcut and into their rooms.

 -----

Gaster tried to protest when Sans installed him on the couch. The shorter skeleton’s glare ended that. He watched, bemused, as Sans retreated into their bedroom. He returned with an armful of blankets larger than he was. The blue glow explained how he’d managed to carry it. It also provided the means for Sans to wrap him in a small blanket nest without dropping anything.

Surveying his handiwork, Sans apparently decided there weren’t enough. He stalked into Papyrus’ bedroom with a determined look on his face. Gaster was sure Papyrus would forgive the intrusion, given the circumstances. He was quite the caring monster, and he probably always had been.

The second load of blankets having been arranged to his satisfaction, Sans wriggled in next to him. This was made easier by the absorptive qualities of his new goop. Sans seemed perfectly happy to be literally wrapped in him, and who was Gaster to judge?

“okay, doc, since you are the invalid of the day, what are we gonna watch?”

Gaster snorted. So that’s what this was. When Sans had been in the later stages of carrying their offspring he’d always been cold and always been bored. Tying him up and burying him under a heap of blankets on the couch to marathon human tv had been Gaster’s favorite method to keep him happy. Now Sans was using the same tactic on him.

Carefully, paying attention to every syllable, Gaster asked him, “Are there any decent science shows available?”

Sans shrugged, “think mythbusters might be playing. let’s…”

Gaster giggled. The remote was on the coffee table a few feet away. If Sans’ arms hadn’t been trapped inside both blankets and goop, he might have almost been able to reach it. As it was, it might as well have been in the VOID.

“I_i’ll get it.”

Gaster frowned at his slip. He needed to be better than that. More practice was in order, it seemed. But not now. Now, he summoned an appendage outside of the blanket nest and used it to retrieve the remote. Turning on the TV, he navigated from Papyrus’ favorite cooking network and over to his and Sans’ own favorite channel. Mythbusters was, indeed, marathoning. They were quite fun and interesting, if sometimes excessively interested in exploding things. He set the remote down and settled in.

Sans kissed his cheek at the start of the commercial break. He swiveled his skull to face his smaller lover. Sans looked exhausted and worried. Gaster smiled and kissed his cheek. He understood. He would have been the same way had he lost Sans.


	5. Day 5: In the Lab

Gaster winced as he bumped into yet another doorway. Sans had insisted on blindfolding him. He was quite willing, but in his enthusiasm Sans kept dragging him into doorframes. Gaster had mixed feelings about doorframes, as one might expect. Being slammed into them wasn’t helping.

Sans slid to a stop in front of him causing Gaster to run into him. The blindfolded skeleton assumed they had arrived at their destination. This hypothesis was confirmed when Sans removed the scrap of fabric from around his skull. He blinked his sockets clear and took in his surroundings.

The floor was a seamless, waxed expanse of blue and purple flecks over a white background. The walls were had the same material as the floors swooping up to the level of his shoulders, which would be just a bit over four feet. Above that was a vertical pinstripe pattern of white with purple and blue stripes. Gaster approved of the color scheme - how could he not?

Two of the four walls had counters along them. Black tops over polished metal looked professional without being visually unappealing. The metal was worked to the point of reflectivity, which allowed Gaster to see the reflection of real things, colors, and shapes - all of which would have impossible in the VOID. Someone who knew of Gaster’s recent aversion to all things grey had clearly been involved in the design. He suspected said person was short, adorable, and blushed blue.

One of the other walls was less wall and more window. A giant bank of windows, to be precise, with a view that humans might have taken for granted or even disliked. There was a warehouse covered in graffiti blocking one half of the view. The other half was a stretch of asphalt with pipes and rebar sticking out at odd intervals inside the collapsing remains of brick walls, along with straggly bits of greenery and a determined blackberry thicket. Train tracks stretched out parallel to the windows on the far side of the warehouse. Beyond them was a concrete river with more graffiti on the sides. A highway swarmed beyond that, cars blaring and screeching and roaring as they always seemed to do. More industrial buildings lay beyond that.

In Gaster’s eyes, it was perfect. Wasting ground on warehouses and emptiness was alien to the space-starved Underground. Blackberry bushes were impossible to kill, and their sheer stubbornness made him optimistic for the future. The graffiti was colorful and varied, some vulgar, some artistic. It would always be changing, and it was about as far from the dullness of the VOID as one could get. The sounds and sights of the trains and cars would entertain him for hours. The river, while contained, was free and clear - a reminder of the Underground and that they were no longer trapped there. And beyond it all? The sky, with its ever-changing humors and brilliant sunlight. What monster could want anything more?

Tearing his sockets away from the view took effort, but the rest of the room deserved to be viewed. The wall with the door had one long desk, complete with two computers, on the side closer to the windows. The desk was angled so that both occupants could look out the window any time they pleased. There was a printer, a filing cabinet, and a shredder there, too.

The other section of the last wall, the side adjacent to one of the counter walls, was one giant whiteboard. It was the kind seen in lecture halls around the world - three layers that could be rolled up and down to provide plenty of space to work with. Always a good thing when math might be involved. That and doodling. There was also a chemical shower, which fit with the theme.

The interior of the room had lab tables, a sink, a vacuum chamber, a fume hood, a freezer, a...well, it had anything and everything a scientist might need. There were microscopes - regular, molecular, and magical. There was a mass spectrometer and an automatic piper. There were tinkering tools aplenty, although that had always been more of Alphys’ specialty than his. Still, he’d never have built the CORE if he hadn’t been willing to get his hands oily.

Gaster turned his skull to Sans. Tears were streaming down his face. If someone had asked him what the perfect gift would be, this lab would be it. Sans was positively beaming. He knew he had done very well.

“i take it you approve?”

Gaster nodded, his voice momentarily escaping him.

“good. i thought you’d like it, but...well. i wasn’t sure if science was a bad memory.”

Gaster shook his head so hard the tears went flying. It was a good thing the floor was so easy to clean.

“truth is, i’ve been kinda looking forward to it myself. fixing that machine made me remember all of the reasons i loved helping you in the first place. the math, the theorizing, the collaboration, the tinkering...i missed it. so wha’d’ya say, doc? i’d love to be your assistant, just like old times. d’you want me?”

Gaster wanted to accept. For a split second, he was going to. But something in that speech held him back. Sans had done so much for him over the years. Rescuing him was hardly the start of it. Didn’t the skeleton deserve better than this?

Slowly, Gaster spoke. He didn’t mess up with his voice nearly as much nowadays, but now more than ever he wanted to be understood.

“I will always want you, my love. But I cannot accept,” Gaster held up a hand to prevent Sans inevitable protest, “I would love to work in a lab again. But I will not be the head scientist. That part of my life is finished.”

Sans looked grudgingly confused. An interesting expression, to be sure.

“i don’t think alph will want the job, gaster. she’s-”

Gaster interrupted him, a rare occurrence of late, “No. It should be you,” Sans’ expression shifted to panic, “You did so much work in the old days. Do not try to tell me otherwise. Your designs were always brilliant, even when they failed. And they failed rarely. You proved that when you rescued me. I know how much effort you put in. You are far from underqualified. I am not the only one with a PhD, remember? I would love to be your assistant.”

Gaster coughed, a little embarrassed at the look of adoration Sans was aiming at him.

“In any case, your handwriting is far more legible than mine will ever be. I am sure humans will appreciate not having to translate Wingdings. I know you did.”

Sans let his skull fall, but Gaster saw the tears hitting the floor.

“heh. never would have thought you’d say that, g. especially after...you know. but you really mean that, don’t you? you want me to take the lead. i...okay. i’ll give it a go. but if things blow up in our faces, remember this was your idea. got it?”

Gaster nodded, his eye lights twinkling. There was his Sans.

The smaller skeleton shuffled his moccasin-clad feet. Somehow those were enough of an improvement over his slippers for the rule-loving humans to pass judgement.

“can we work on a transdimensional beacon system? you know...just in case.”

Gaster smiled down at his sweetheart of a lover. Only Sans would pick as his first project in a brand new lab something so similar to, and yet so different from, the one that had nearly broken him.

“Of course, Doctor Sans,” he placed emphasis on the title, making Sans shiver with the unfamiliar taste of it, “After all, I have no idea what I would do if I lost you again.”

He kissed the top of Sans’ head, then sloughed over to the filing cabinet. He started searching for the relevant file, smiling at the feeling of adoration radiating from the skeleton behind him.

**Notes for the Chapter:**

> Tomorrow might be late. I hope it won't, but it might.


	6. Day 6: AU

**Notes for the Chapter:**

> Sorry this is late. I got hit with a bug that turned me into a puddle of sleep for 18+ hours a day. The other six were split between food and moving my brother into his dorm. The next chapter should be done soon, too.

It had been at least a year since Gaster had returned, and yet in some ways it felt like he’d never been gone. He could move faster than Sans now and had far more energy and stamina than Sans did. His voice hardly ever acted up anymore. Well, every week at the PTA meetings it did. Sans suspected his boyfriend might be doing it on purpose. Helen just...deserved it, okay? 

 

Gaster’s goopy body was even starting to firm up a bit more. Sans wasn’t sure how he felt about that. On the one hand, Gaster used to be so tall compared to him, and he’d liked that. He could wear clothes, too. Also sidewalk grates weren’t an issue for someone with actual feet. But on the other hand, Sans wouldn’t be able to snuggle him on every side! So much to think about.

 

Right now he had to think about the wiring in front of him. Messing this up might take the whole world and invert it through a black hole! Or, you know, just suck him through to the eerie VOID and strand him there, alone and unrescuable, for eternity. Thus, focus.

 

He and G had built a more user-friendly interface for the door. At first they hadn’t wanted to touch it, but they were scientists, damn it! It was just too irresistible to ignore! The grants committee had agreed. Sure was nice to have a budget that  _ didn’t  _ involve two hours of drinking bitter tea. Not that Asgore’s tea was  _ bad _ . Sans just didn’t like tea.

 

After the beacons had been tested as much as was possible in the same time-space reference, they’d decided they wanted a backup before a full-scale test. So now there was a screen the same height as the door frame that attached to one side. It would display the connection point’s coordinates (including the Cartesian distance from this point as a rough estimate of the potential scope of change); it also had less technical things like the temperature, the humidity, the magic supply...you know, stuff that might make it a bad idea to step through the door. No one would want to pass through only to realize the atmosphere was so hot their SOUL melted. That would be a bad thing.

 

Just as Sans thought he’d gone thing hooked up properly it started flashing red. Why was it doing that? The background was supposed to be blue when it was inactive, green when the connection was safe and stable, and yellow when it was dangerous or deadly. Bright red wasn’t in the programming, unless Gaster had added something without telling him. Sans decided the logical course of action here was to scramble across the room and hide behind Undyne’s Pile o’Armour.

 

The screen kept flashing red long enough for Sans to consider getting out his phone and asking G if he’d actually written this in. Then it stopped flashing and just stayed red. Sans felt like that signalled a settling of something. Apparently it had settled on letting the impossible happen.

 

The door opened. It opened, and not only did it open on its own, which wasn’t supposed to happen, but it opened the wrong way. The hinges shouldn’t let it swing like that. It also slammed open, which, while possible, wasn’t a good sign.

 

The doorway framed the hated grey of the VOID, only this time the grey was tinted red. If someone had put matte red sequins into a fog machine the result would probably have looked something like this. The doorway also framed a black blob with a grey skull on top and a crumpled figure in its arms. The blob flung itself and its burden out of the doorway. At least, they were flung out of the doorway. The way the door slammed shut behind them made Sans wonder if they’d been moving under their own power in the first place. 

 

The grey skull surveyed the room in jerky, paranoid motions that left Sans with a fleeting impression of cracks far deeper than Gaster’s own on a skull far sharper and smaller, as well as shorter in height. The figure in its arms was almost swallowed up by the dark body in a protective cocoon. Sans couldn’t see much. A skeletal leg with yellow socks and untied red converse hung limp. A bit of a ratty blood-and-dust stained, fluff-lined hoodie poked out. An arm with a sliver of a red-knit sweater under a black leather jacket dangled loosely. Blood dripped off the clawed hand.

 

Grey-skull, having decided that nothing in the basement posed an immediate threat, proceeded to glow a faint, sickly green around the unconscious skeleton. He also made a noise like a cross between a coo and a croon. It was comforting in a weird sort of way. It gave Sans the courage to make himself known. He stood up, being careful to move slowly and unthreateningly.

 

“hey, uh, weird dude who came out of the…”

 

Grey-skull had three reactions to this speech in quick succession. The first was to look down at the figure in his arms with joy and hope. Then he realised it wasn’t his...friend? Sure, let’s go with that. Since his friend wasn’t stirring, let alone speaking, he looked around the room for the source of the noise. And by looked, he meant frantically searching while hyperventilating loudly. When he spotted Sans that fear melted into aggression. One blaster manifested with the left half of its skull missing and hundreds of spikes on the other side. Another tried to manifest, but shattered within a split second. The shards, rather than disappear, rotated and spun to face Sans with their jagged edges. 

 

“woah! easy there, bud. i ain’t gonna hurt you. see?”

 

Sans raised his hands and let his magic dissipate despite the tense atmosphere. The strange monster eyed him warily.

 

“i ain’t gonna hurt you,” Sans repeated himself in a quieter tone laden with conviction. He stepped towards the pair only for a pair of bone shards to leave holes in his favorite jacket. He took the hint, “sorry. i’ll stay over here then.”

 

Grey-skull eyed him incredulously, clearly waiting for an attack. Sans wondered what kind of a place he came from. The War, maybe? Some really, truly horrible future? He hoped it wasn’t the latter.

 

A minute passed. Two. The attacks weren’t fading. 

 

“look, it’s clear you don’t trust me. i get that. you’ve clearly been through something horrific. maybe several somethings. but your friend looks like he’s really hurting, and while i’m no tori,” the figure stepped back, his confusion growing, “i do know a bit of healing magic. do you mind if i lend a hand? or at least call someone else in? your buddy’s oozing.”

 

It was true. The smaller skeleton in the figure’s arms was dripping a red puddle on the concrete. Sans wasn’t sure if it was ketchup, blood, magic, or DT. He really wished it wasn’t a question he needed to be asking. 

 

Grey-skull gave this considerable thought. In his expression, Sans saw logic and desperation war with fear and ingrained distrust. The red puddle had doubled in size before the figure came to a decision. 

 

“Yy#ooo0o#u. T##ttTo#riiEl. Hh#Elp#P.”

 

Sans’ SOUL hurt at the torment obvious in his voice. This monster had been pushed beyond his limits three times over. The only reason he was doing this was for the skeleton in his arms. On his own behalf he would have let himself dust. 

 

“alright. i’m just going to text her to come over, kay?”

 

Grey-skull nodded. Slowly, letting the foreign monster see every move, Sans fished the cell out of his pocket. He unhooked the stylus and typed out a message. 

 

-yo, tori.  _ goat  _ to be a bother, but i've got a bit of a problem. two, actually. skeletons. never met them before, but one’s really badly hurt. can you come down to the basement and lend them a paw?

 

She didn't bother to text him back. However, the stain remover falling from the ceiling joists told him she was running. He'd have to thank Undyne for getting the powder stuck up there in the first place.

 

“okay buddy. all done. are you ready for me to walk over and help... uh, what's your bud’s name again?”

 

Grey-skull extracted the smaller skeleton with immense care. The sudden sender of discombobulation and vertigo hit him when Grey-skull spoke the name. 

 

“Ss#AaaAn#Ns.”

 

Noticing his confusion (or perhaps taking advantage of it?) the stranger added, “I aaa#Am GAa#asSss#stTerR.”

 

A gasp from the staircase signaled Toriel's arrival. Her paw was on her mouth being stained by green tears. Grey-skull seemed just as shocked as she was. 

 

“M#my QqQquee#EEen#n…?”

 

Toriel gulped and shook her head. 

 

“No. I have not gone by that title in years...Although perhaps...Your Toriel maintained it?”

 

Sans supposed it was easier to come to that conclusion when you weren't staring your unconscious Doppelganger in the sockets. Of course,  _ she  _ had the benefit of two skulls to examine. Sans had only had Grey... The other Gaster's. 

 

Said skeleton hung his head. Toriel made that little sound that universally indicated sympathy and understanding. Maybe even multi-universally. Heh. That was funny. 

 

Toriel swept past the now hysterically giggling skeleton she lived with and took the injured version of him in hand. She swallowed, although Sans couldn't see why with her back turned to him. Then again, he was kinda having a mental breakdown at the moment. Hard to see through all the fuzz.

 

She croaked, “What happened to him?”

 

“I#ii… Aam#m nNNNo#ot sssssSur#re. Iii w#wWas#s tTtTtrrR#AaaPed...the#enN IIiiIIi fF#foOun#nNnd h#hHhiIIm#m.”

 

Toriel gulped and breathed out a slow, controlled stream, “I see. I suppose he will have to tell us himself once he comes to. I am going to stabilize him as much as I can. Then I believe transferring him to a bed somewhere is the next step. I believe appartment 613 is unoccupied. Sans, can you…”

 

Her voice trailed off as she realised the dual problems of referential uncertainty and comprehension. There were two Sans in her immediate vicinity. Neither of them were in a state to listen.

 

“We shall have to get the key on our way upstairs. You are going to stay until you both are healed, are you not?”

 

Gaster looked lost and confused when Sans finally managed to unbend enough to see, “Iii...dD#do nOoOOt#TT thiII#inKk w#wwEee hAav#ve a choOOOic#c#ce.”

 

Toriel’s gasp died in mid-sound, “I suppose that might be the case. I believe it took quite the effort for Sans- my Sans- to bring his Gaster out of the VOID. It may take some time for them to figure out how to send you home...assuming that you do not wish to stay. The Surface is quite an amazing place.”

 

The other Gaster looked stunned. His mouth opened and closed a few times. Then tears the same sickly-green shade as his magic had done. The resulting expression was nostalgic bordering on overjoyed.

 

“T#tttheE SssS#sur#rFfAaace?” Toriel nodded. The newly-arrived Gaster turned his skull to the skeleton in his arms, “Ss#AaaAn#Ns! I#i c#C#caAn fFFfinAAAl#LLy shOow y#YYyo#U theEe s#SSst#t#TtaAar#rS!”


	7. Day 7: Free Day

Two years had passed since Gaster had been freed. It felt like only yesterday. It felt like a hundred years. At times, it felt like both at once. 

 

Settling all their new neighbors from other dimensions had taken so much time and energy. Sans was sure they were far from done. After fifteen monsters, it was almost inevitable there would be more. But Toriel had put her foot down and told Sans and Gaster in no uncertain terms that they were to take a vacation. Sans wasn’t sure how long they’d be gone. The former queen had told them to stay away until she texted them to return. Who knew when that would be.

 

She’d been rather startled when Gaster informed her that they would be visiting the Underground. She’d expected the beach or the rainforest or the desert - something exotic, something full of scientific potential, something...not the Underground. Not many monsters wanted to go back there.

 

The moment Gaster said it, though, Sans knew why. There was something, no, some _ one _ down there who had been waiting long enough. And finally, finally, they could see the stars.

 

* * *

 

Lights shone in a place they hadn’t been for years. The dust that had sat thick when last those lights had been on was gone. It had been banished with thoroughness and finality. It had no place here. Not now.

 

The space that once held such melancholy was completely transformed. Medical equipment had been wheeled out of storage. Stats monitors were blinking. IVs were dripping. A floating skull with closed sockets was stationed idly to the left of a small, mobile medical bed. An  _ occupied _ medical bed. 

 

The small skeleton who once was suspended in the empty tube against the wall was laid out with care on the flowered sheets. They were still unconscious, although not for much longer. The two skeletons who were passed out at their bedside were more than ready to welcome them to the world. At least they would be when they woke up.

 

Two eye sockets blinked open. The eye lights inside were doubled for a moment, two sets stacked one on top of the other. Then the sets merged. They narrowed, then widened, then narrowed again. The skull they were set in turned to the right with rather more speed than care. Then it turned 180 degrees in the other direction. Unfortunately, it was large enough to budge the entire bed it rammed into a good two feet.

 

Like a Rube Goldberg machine, the moving cot set off a chain reaction, or, more accurately, two. First, the floating skull that had hit the bed jerked back. It hit the wall. When it did the small skeleton in the cot, who had been twitching along with every move the Blaster made, gasped. Their hands flailed up in front of their face. Their knees came up as well.

 

The second chain reaction moved in the opposite direction. The thrust of the cot sent a solid ripple through the goop of Gaster’s Void-changed clothes. His skull popped out with eye lights almost as wide as his sockets were.

 

“Ee_eeE-!”

 

The screech woke Sans where the ripples had not. He blipped out of his position collapsed into Gaster’s back. He also blipped out of the room, but it was less than a second before he was back. He swore from the doorway before blipping over to the Blaster. He held up his hands and projected as much calm and affection as he could.

 

Over at the cot, Gaster was picking up their child and cuddling them with the same emotional projections Sans was using. He was also cooing in the way all creatures coo at small, young things. 

 

The echoes of that eerie screech warbled their way through pipes and tunnels all the way to The Ruins. In that time only cooing and calming were on the minds of the couple in the lab. But once the sound had reached that final beginning, the child in Gaster’s arms finally settled down. 

 

Two hands with holes in their palms unclenched from their defensive position in front of the child’s skull. No sockets were visible; the bone had never parted to form them. The nasal cavity was without any true point and took up rather more face than expected. The smile was long and narrow, but Papyrus’ detached jaw had come through. 

 

Other than that, it was hard to tell what their child would turn into. Anything was possible, especially considering the veritable army of powerful monsters (and one very determined human) who would stand beside them. They had already overcome so much. Without sockets, the babybones was certain to be blind forever. But with a very large, very fierce, and very literal seeing eye skull, the world was now theirs to observe.

 

* * *

 

Sans wasn’t exactly sure if what they were doing would disobey Toriel’s ‘vacation’ order. Honestly, though, he didn’t care. It wasn’t like they were working. But they weren’t where they’d said they’d be. They weren’t even that far away. Or would it be up?

 

The top of Mt. Ebott was a different place than it had once been. Even ten years ago no living being would willingly set foot on the mountain. But then there was Frisk. Frisk had changed everything, but this place, perhaps, was the easiest to see. A permanent platform had been sculpted out of the alpine slopes. Parking spaces lined the inner side of it; railings lined the other. Benches small and large were scattered near the edge. Telescopes, too. 

 

The fact that no one was up here tonight absolutely shocked Gaster. He’d never been up here in winter before, when the cold and slippery slopes made the trek up the mountain just that little bit less appealing. Humans could be put off by stuff like that - monsters, less so. But from what Sans could remember, today was test season for the school system. Those monsters that didn’t have midterms or finals of their own likely had a child or two busily studying. Not the night for a trip to see the stars.

 

Their loss. The cold air and lack of any pressure front left the sky crystal clear and cloudless. The Milky Way actually  _ looked _ like all those illustrations in magazines and textbooks. They couldn’t have asked for a better way to introduce their kid to the stars.

 

The floating blaster was tilted almost straight up. Its sockets were as wide as they could go. Huffs of sound that walked the line between chirps and buzzes vanished in the night air. Gaster kept trying to convince Sans that they were one of the more symbolic fonts. Sans just smiled. Their kid was still way too young for real words. 

 

He wasn’t going to rush them. Let them find their own way in their own time. After all, they had more stars than could be counted to guide them. Even from their place in Gaster’s arms, they were already reaching out to touch them. 


End file.
